In-line liquid sterilizers have commonly been used in the food industry, for example, for processing dairy products. A typical in-line liquid sterilizer uses a standard water start-up/product chase method. The system is flushed using water before the initiation of sterilization of the product to remove any impurities in the system as the system is brought up to the desired operating temperature. Once the heat-exchangers of the system, typically employed for both heating and cooling, are operating at the desired temperatures, product to be sterilized is introduced to "chase" the water from the system, and product sterilization is initiated.
Inevitably, when the product is initially passed through the system, the water and product mix. Thus, initially, a large quantity of product must be discarded due to dilution by the water. After the flow of product causes the water to be completely removed, the undiluted product passes through the system and sterile product is produced.
This type of in-line liquid sterilizer is not practical for use in the pharmaceutical industry. The design does not address all pharmaceutical standards and requirements. In particular, the standard water start-up/product chase method is not advantageous for sterilization of relatively expensive pharmaceutical products since a relatively high volume of product loss during start-up typically occurs. Such systems also result in undesirably high product losses during system shut-down.